1,3-bis(4-chlorophenyl)-2-propen-1-one guanylhydrazone hydrochloride and analogs thereof useful as antimalarials

ABSTRACT

The disclosure describes three analogous compounds, 1,3-bis(4chlorophenyl)-2-propen-1-one guanylhydrazone hydrochloride, 1,3bis(4-chlorophenyl)-2-buten-1-one guanylhydrazone hydrochloride, and 1,3,3-tris(4-chlorophenyl)-2-propen-1-one guanylhydrazone hydrochloride. The compounds are useful in the prevention and treatment of malaria.

United States Patent 1 Henry 51 Apr. 10, 1973 [54] 1,3-BIS(4-CHLOROPHENYL)-2- [56] References Cited PROPEN-l-ONE GUANYLHYDRAZONE UNITED STATES PATENTS HYDROCHLORIDE AND ANALOGS 2,815,377 12/1957 Mciser et a1 ..260/564 THEREOF USEFUL AS 2,952,677 9/1960 Birtwell et a1. ..260/564 F x ANTIMALARIALS 3,130,232 4/1964 Paquette ..260/564 [75] Inventor: David W. Henry, Menlo Park, Calif. Primary Examiner-Leon Zitver Assistant ExaminerGera1d A. Schwartz [73] Assignee Umted States 0f Amenca as Attorney-Charles K. Wright, Jr., William G. Gapcynrepresented by the Secretary of the ski and Lawrence A. Neureither Army [22] Filed: Jan. 6, 1970 ABSTRACT [21] Appl No: 1,061 The disclosure describes three analogous compounds,

1 ,3-bis( 4-chlorophenyl )-2-propen- 1 -one guanylhydrazone hydrochloride, l,3-bis(4-chlorophenyl)-2- [52] U.S. Cl. ..260/564 F, 424/326 buten-1- ne guanylhydrazone hydrochloride, and [51] Int. Cl ..C07c 129/00 1,3,3-tris(4-chlorophenyl)-2-propen1-one guanyl- [58] Field of Search ..260/564 F hydrazone hydrochloride. The compounds are useful in the prevention and treatment of malaria.

1 Claim, No Drawings l ,3-BIS(4-CHLOROPHENYL)-2-PROPEN-1-ONE GUANYLHYDRAZONE HYDROCHLORIDE AND ANALOGS THEREOF USEFUL AS ANTIMALARIALS The invention herein described was made in the course of or under a contract or subcontract thereunder with the Department of the Army.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to l,3-bis(4-chlorophenyl)-2- propen-l-one guanylhydrazone hydrochloride and analogs thereof, useful in the prevention and treatment of malaria. More specifically, it relates to three new antimalarial compounds, l,3-bis-(4-chlorophenyl)-2- propen-l-one guanylhydrazone hydrochloride, 1,3- bis(4-chlorophenyl)-2-buten-l-one guanylhydrazone hydrochloride, and l,3,3-tris(4-chlorophenyl)-2- propen-l-one guanylhydrazone hydrochloride.

Description of the Prior Art Malaria is one of the most widespread of all human diseases; it has been estimated that over 200 million people are afflicted and over a million die each year from malaria. Furthermore, contrary to popular belief, malaria is not confined to the tropical and subtropical regions; outbreaks have occurred almost as far north as the Arctic Circle and to a corresponding latitude south. It is a protozoan disease caused by several species of the genus Plasmodium which forms one of the families of the sub-order Haemsporida. Plasmodium vivax and Plasmodium falciparum are the most common species causing malaria in humans.

A number of antimalarial compounds have been prepared in the prior art, see for example the antimalarials section in Remingtons Pharmaceutical Sciences, 13th edition (1965), pages 1302-1306. Recently, however, the prior art antimalarials have proved to be ineffective in specific cases in various parts of the world. The World Health Organization Technical Report No. 296 1965 entitled Resistance of Malaria Parasites to Drugs, reports the following cases of drug resistance: quinine sulfate failed completely against strains of Plasmodium falciparum from New Guinea; chloroquine, amodiaquine, mepacrine, pyrimethamine and proguanil gave poor results against Plasmodium falciparum and Thailand; chloroquine, mepacrine, pyrimethamine and proguanil were ineffective against Plasmodium falciparum from Cambodia; Plasmodium falciparum from Vietnam proved resistant to chloroquine; and chloroquine gave poor results against malaria in Malaya. Further instances of drugresistant malaria may be seen in L. Bruce-Chwatt, Trans. Roy. Soc. Trop. Med. Hyg. 59, 105-144 (1965), in L. Legters et al., Military Med. 130, 168-176 (1965), and in A. Bourke et al., Trans. Roy. Soc. Trop. Med. Hyg. 60, 225-230 (1966 The only conclusion to be drawn from these reports is that there exists a great need for new antimalarial drugs.

SUMMARY OF THE INVENTION This invention comprises the preparation of three new compounds and the discovery that these new compositions of matter are effective antimalarials. The

three new compounds, 1,3-bis-(4-chlorophenyl)-2- compounds shown antimalarial activity that is completely unexpected.

Accordingly, it is an object of this invention to prepare new compositions of matter that are analogs of l,3-bis( 4-chlorophenyl)-2-propen- 1 -one guanylhydrazone hydrochloride.

Another object of this invention is to prepare new compositions of matter that are analogs of l,3-bis(4- chlorophenyl )-2-propen- 1 -one guanylhydrazone hydrochloride and that possess antimalarial activity.

A further object of this invention is to provide new processes for the prevention and treatment of malaria in mammals, and particularly in humans, wherein the active ingredients are new analogs of 1,3-bis( 4- chlorophenyl )2-propen- 1 -one guanylhydrazone hydrochloride.

Finally, it is an object of this invention to prepare new compositions of matter that will be active against drug resistant malaria.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The new compositions of matter in this invention are prepared as follows:

EXAMPLE 1 Preparation of 1,3-bis(4-ch1orophenyl)-2-propenl one guanylhydrazone hydrochloride The first step in synthesizing the desired end product was to prepare the intermediate, 4,4- dichlorobenzalacetophenone. This intermediate was prepared according to the general procedure of E. P. Kohler and H. M. Chadwell in Organic Synthesis, 2nd edition (1948), Collective vol. 1, page 78, by reacting 4-chloroacetophenone and 4-chlorobenzaldehyde. The intermediate product was obtained in 83 percent yield and with a melting point of l53l55 C. which compares favorably with the melting point of l55-l57 C. reported by H. 0. House, Journal American Chemical Society, vol. 78 (1956), page 2298, for this intermediate compound.

The next step in the preparation of the desired end product was to slowly add amenoguiridine bicarbonate to a solution of 30 concentrated hydrochloric acid in 12 ml. of water. After the evolution of carbon dioxide had ceased, the intermediate 4,4- dichlorobenzalacetophenone and ethyl alcohol were added. This suspension was refluxed with stirring. The precipitate was the desired end product, 1,3-bis(4- chlorophenyl)-2-propen-l-one guanylhydrazone hydrochloride. It was recrystallized from ethyl alcohol and gave a melting point of l43153 C. The preparation resulted in a 14 percent yield. Thin-layer chromatography using silica gel and 10 percent methyl alcohol in chloroform revealed one component with an R, of 0.25.

An elemental analysis gave the following results: Analysis calculated for C I-I Cl,N -I-ICl: C, 52.0; H, 4.09; N, 15.2. Found: C, 51.9; H, 4.20; N, 15.2.

EXAMPLE 2 Preparation of 1,3-bis(4-chlorophenyl)-2-buten-1-one guanylhydrazone hydrochloride In the preparation of 1,3-bis(4-chlorophenyl)-2- buten-l-one guanylhydrazone hydrochloride, it was necessary to prepare the intermediate, 1,3-bis(4- chlorophenyl)-2-buten-l-one. This intermediate was prepared by the procedure of E. Ziegler and H. Schredt, in Monatsh. Chem., vol. 85 (1954), page 1191; Chemical Abstracts, vol. 50 (1956), page 321. 4- Chloroacetophenone (74 g., 0.51 mole) and 45 ml. of phosphorous oxychloride was held at 45 C. for hours and then at 25 C. for 10 hours. The brown solution was poured over cracked ice and the oily product was extracted with ether. The ethereal solution was washed with water and dilute sodium carbonate solution and concentrated to yield 70 g. of oil. The crude product was dissolved in 150 ml. of ethyl alcohol and the solution was seeded. The crude yellow l,3-bis(4- chlorophenyl-Z-buten-l-one melted at 75-l07 C. Two triturations with 500 ml. portions of methyl alcohol gave 16.5 g. (24 percent yield) of the intermediate, l,3-bis(4-chlorophenyl)-2-buten-l -one, melting at 75-80 C. This compares favorably with the report of Ziegler and Schredt, above, who gave a melting point of 80 C. for this compound.

Continuing in the preparation of the desired end product, aminoguanidine bicarbonate (3.0 g., 0.022 mole) was slowly added to a stirred solution of 32 ml. of water and 2.6 ml. of concentrated hydrochloric acid (0.031 mole). When the evolution of carbon dioxide ceased and the solution cleared, 6.0 g. (0.022 mole) of the intermediate, l,3-bis(4-chlorophenyl)-2-buten-1- one, was added along with 50 ml. of ethyl alcohol. The mixture was refluxed overnight (solution attained) and then heated five hours longer. It was cooled and some of the ethyl alcohol was removed in vacuo. The precipitated solid which resulted was collected and titrated with diethyl ether to give 4.93 g. (59 percent yield) of the desired end product, l,3-bis(4- chlorophenyl )-2-buten- 1 -one guanylhydrazone hydrochloride, melting at 235238 C. A portion of the product was recrystallized from 1:1 ethyl alcoholwater for an analytical sample melting at 245-246 C.

An ultraviolet spectrum analysis gave the following results: A f 207 my. (6 31,300), 274 m (c=31,300).

An elemental analysis gave the following results: Analysis calculated for C H Cl N -HClz C, 53.3; H, 4.47; N, 14.6. Found: C, 53.1; H, 4.53; N, 14.8.

EXAMPLE 3 Preparation of 1,3 ,3-tris(4-chlorophenyl)-2-propen-1- one guanylhydrazone hydrochloride The first step in the preparation of 1,3,3-tris(4- chlorophenyl)-2-propen-l-one guanylhydrazone hydrochloride was to'prepare the first intermediate 1,1- bis(4-chlorophenyl)ethylene. This first intermediate was prepared by the addition of methyl magnesium bromide to 4,4-dichlorobenzophenone and subsequent dehydration according to the procedure of O. Grummit et al. in Journal American Chemical Society, vol. 67 (1945), page 2265. The first intermediate 1,1- bis(4-chlorophenyl)ethylene was obtained in an 80 percent yield with a melting point of 8388 C. which compared favorably with the results of Grummit et al., supra, who reported an percent yield with a melting point of 84-85 C.

The next step in the preparation of the desired end product was to prepare the second intermediate 1,3,3- tris(4-chlorophenyl)-2-propen-1-one. The procedure used to prepare this second intermediate is a modification of the general method of F. Bergman et al. in Journal Chemical Society, 1952), page 2522.

A solution of 17 g. (0.0683 mole) of the first intermediate l,1-bis(4-chlorophenyl)ethylene and 13.15 g. (0.0751 mole) of 4-chlorobenzoyl chloride was heated to 240 C. At this temperature hydrogen chloride vapor evolved. The hydrogen chloride vapor was swept from the flask by a slow stream of nitrogen gas and monitored by bubbling through a sodium hydroxide solution containing phenolphthalein indicator. After about 18 hours, hydrogen chloride evolution ceased. The result ing black, solid reaction mixture was extracted with ethyl alcohol several times and the extracts were filtered. The solvent was removed from the combined filtrate and the residue was chromatographed on silica gel. Elution with carbon tetrachloride yielded starting materials and by-products. Elution with chloroform then gave 5.15 g. of moderately pure product, which was recrystallized several times from ethyl alcohol to yield 2.0 g. of pure product with a melting point of l40 C. Thin-layer chromatography using silica gel and carbon tetrachloride showed one component with an R,of0.l8.

An ultraviolet spectrum analysis gave the following results: A 233 mp. (e 22,000), 271 my. (e= 18,600), 318 mu (e= 14,000).

An elemental analysis gave these results: Analysis calculated for c,,u,,c1,o= C, 65.1; H, 3.38. Found: C, 65.6; H, 3.45.

The final step in the preparation of the desired end product was to slowly add aminoguanidine bicarbonate to a solution of concentrated hydrochloric acid in water. After the evolution of CO, had ceased, the second intermediate 1,3,3-tris(4-chlorophenyl)-2- propen-l-one and 46 ml. of ethyl alcohol were added. This suspension was refluxed with stirring for 16 hours. The initial preparation of this compound gave analytical samples of both a dehydrated (melting point -170 C.) and an unhydrated (melting point 210220 C.) product. A second preparation gave 1.5 g. (43 percent yield) of hydrated product.

An infrared spectrum analysis gave the following results: A 2.95 3.25u (NH functional group) and 5.96 (C=N functional group).

An elemental analysis gave the following results: Analysis calculated for C,,H Cl,N 'HCl-H,O: C, 53.0; H, 4.01; N, 11.2. Found: C, 52.8; H, 4.21; N, 11.4.

ANTIMALARIAL UTILITY The three new compositions of matter prepared in the above examples show unexpected and unobvious' Research primary mouse screen test on a series of analogs of 1,3-bis(4-chlorophenyl)-2-propen-l-one guanylhydrazone hydrochloride.

ANTIMALARIAL EVALUATION OF COMPOUNDS Antimalarial bionssay results '20 40 S 100 320 040 Example Structure lug/kg. nigJkg. lug/kg. nun/kg? Inga/kg. 1ng./kg.;

1 0.4 5.0 0.6 17.0 C -35 C C Gl- *CH=CH(|T -01 ll NNHONH2 .HCl

01 O=CHC -Cl l 1.0 4.6 14.9%C 19.4%0 23.9%(3 A0 CH3 I l NNH |I|1NHa CI (IJ=CHF Cl I NNHgNHz 1 Increase in survival time (in number of days) of treated mice beyond that of untreated controls after single subcutaneous dosages (three days post-infection) of 20, 40, 80, 160, 320 and 640 mg. of drug per kg. of body weight. Average survival time of untreated mice: 6.5 plus or minus 0.5 days.

Infecting organism: Plasmodium berghei. Quinine gives values of approximately 1.0 at 40 mg./kg.,

3.0 at 160 mg./kg. and 7.0 at 640 mgJkg. in this test. A fraction followed by the letter G indicates cured mice over total mice in the treated group. Drug toxicity is assumed to be the cause of death when treated mice die before untreated controls. A dash indicates tests were not run at this dosage. Five mice were used in each test run at a specific dosage level. In some instances, repeat test runs were perform ed.

1 Dosage in milligrams of drug per kilogram of mouse body weight.

The antimalarial evaluation reported in the above table reveals remarkable antimalarial activity in 1,3- bis(4-chlorophenyl)-2-pr0pen-l-one guanylhydrazone hydrochloride (Example 1), l,3-bis-(4-chlorophenyl)- 2-buten-l-one guanylhydrazone hydrochloride (Example 2) and in l,3,3-tris(4-chlorophenyl)-2-propen-lone guanylhydrazone hydrochloride (Example 3).

Testing antimalarial compounds in humans is obviously too dangerous for the first step in the development of antimalarials. Thus, animal tests have conventionally been used to test antimalarial compounds and animal tests have led to the development of many of the antimalarial compounds now available such as quinacrine, chloroquine, pamaquine, and proquanil.

The Walter Reed Army Institute of Research uses the primary mouse screen with Plasmodium berghei for several reasons. One reason is that the Plasmodium species which cause malaria in humans (i.e., Plasmodium falciparum and Plasmodium vivax) cannot live in animals. Another reason is that Plasmodium berghei is regarded as a good model for human malaria. Finally, mice are easy to work with and the Plasmodium berghei infections show the same range of susceptibility to a variety of known antimalarial drugs as other malaria parasites used for evaluating antimalarial compounds. See for example Bull. Soc. Pathol. Exotique 42, 449 (1949); Ann. Trop. Med. Parasitol. 44, 291

(1950); Brit. J. Pharmacol. 8, 162 (1953); Z. Tropenmed. U. Parasitol. 2, 471 (1951 I claim:

1. 1,3-Bis(4-chlorophenyl)-2-buten- 1 -one guanylhydrazone hydrochloride. 

